Typically, moving picture data is converted into bit-stream data by an encoder. At this time, the bit-stream is stored depending on a coding type that satisfies the constraint condition of the encoder.
MPEG, which is the constraint condition of the encoder, requests syntax and semantics.
The syntax, which refers to the structure, format, or length of data, shows the order of expressing the data. In other words, the syntax is to meet the condition for an encoding/decoding operation and defines the sequence, length and format of each data in the elements of the bit stream.
The semantics refers to the meaning of each bit forming data. In other words, the semantics shows the meaning of each element in the bit stream.
Accordingly, various types of bit streams can be generated depending on the encoding condition or the applied standard (or codec) of the encoder. Typically, each standard (e.g. MPEG-1, MPEG-2, MPEG-4, and MPEG-4 AVC) has different bit stream syntax.
Therefore, it can be said that the bit stream encoded according to each standard or encoding condition has different types (i.e. syntax and semantics). A decoder corresponding to a pertinent encoder must be used for the deciding of the bit stream.
As described above, the conventional bit stream decoder has a restriction that must satisfy the constraint condition of the encoder. This restriction makes it difficult to realize an integration decoder corresponding to a plurality of standards.